Police say the homeowner, 63-year-old Jose Santiago Delao, had been running an underground dental clinic in the aging suburban Dallas neighborhood for years: pulling teeth and filling cavities, among other procedures.

As shocking as this sounds, Delao's case is not that unusual. And it offers insight into a world of backyard dentistry that caters to those in the country illegally, the uninsured and others who can’t find affordable dental care.

Delao admits he skirted the law, but isn’t remorseful. “Jesus Christ didn’t need or didn’t have a license,” Jose Delao told Yahoo News during a jailhouse interview. “People hurt and they needed it. People didn’t have enough money to visit the regular dentist.”

Delao, who says he is a trained dental lab technician, says he couldn’t turn his back.

“It broke my heart,” he said, tapping his chest, “because I have the experience.”

But authorities say Delao, a native of Costa Rica, has never been a licensed dentist in Texas. If convicted, he could get two to 10 years in prison.

“This guy was doing some pretty intense work in some cases,” said Plano police Officer David Tilley.

Delao's secret unraveled in mid-January when a woman complained to police about a $75 molar repair that had left her unable to open her mouth and caused a clicking sound in her ear for several days.

The woman, who had gone to Delao on the recommendation of a church friend, also told officers the man kept her from leaving his makeshift clinic once she arrived.

“Jose S. Delao refused to let her leave after he had her in the dental chair,” a detective wrote in a police warrant. "She raised her hand to indicate she was feeling pain and Jose Delao pushed her hand back down and told her to stop complaining."

Any possible assault-related charges are still under investigation. Delao denied the accusations in an interview with Yahoo News.

A survey of published news reports shows that as many as eight such underground dental clinics have been shut down in the U.S. since last summer.

In September, Miami police arrested an 81-year-old illegal dentist whose shoddy work at his home left a 14-year-old girl’s mouth permanently disfigured. Her mother, who had no dental insurance, hoped the man could fix a chipped tooth for cheap. Instead, police said, he filed four of the teen’s front teeth to the gums and left her with a serious infection.

“It just looked awful,” said Catalanotto, whose students and faculty cared for the girl after the incident.

An official with the American Dental Association says it doesn’t track the number of rogue practices, but acknowledged the association has heard stories of patients being treated in vans, warehouses and apartment bathrooms.

“People have extremely serious and unmet needs for oral health care,” said Julia Paradise, an associate director at the Kaiser Commission on Medicaid and the Uninsured.

The Kaiser Family Foundation, a nonprofit think tank focused on major medical issues, reports that the number of adults without dental coverage is three times as large as the number of adults without health insurance coverage and that 30 percent of children with private health insurance are uninsured for dental care. More than 1 in 5 low-income adults reported that they had not had a dental visit in five years or more, or had never had a visit, the foundation wrote in a 2012 study.

Kaiser doesn’t keep stats on unlicensed dentists, but Paradise said it’s troubling to know it’s a choice some patients make.

“The solution is to provide the kind of care and access to care that people need so that there isn’t a space or the need for people to seek care that isn’t safe,” she said.

From behind bars, Delao maintained he was operating safely. “I can pull a tooth,” he told Yahoo. “I have the experience.”

When asked if he ever applied to be a dentist in the U.S. Delao replied, “Not really." But he said he had a four-year degree in dental lab technology from Costa Rica and 27 years of working as a technician in the U.S. Yahoo News could not immediately verify his education or employment history.

Catalanotto said that even should it be true, making molds and dentures as a lab tech doesn’t qualify someone to diagnose patients.

“You’re doing something potentially very dangerous to your health,” Catalanotto said. “You would probably have concerns about infection control issues and catching a communicable disease from unclean instruments. There’s a variety of concerns.”

At least one acquaintance, however, vouched for Delao's character.

“He’s a friendly guy,” said Rubia Albarenga, a travel agent who has known Delao for 10 years. “He has always been honest to us and is a great customer. He was always very respectful. We feel sorry for him.”

Investigators believe that Delao, who lived alone, had been treating people inside his modest 1,500-square-foot home for four years.

He said his cash only, no-questions-asked operation drew one to two patients a day. “I helped undocumented people, single mothers and uninsured people,” he said.

Delao said he charged $50 for what might cost $250 elsewhere. “Only enough to pay my bills,” he said.

Business usually came word of mouth, but news of Delao’s arrest didn’t travel fast enough to stop people from showing up after he was jailed. His neighbor posted a sign on her door, “Aqui No Vive Dentista” (dentist doesn’t live here).

“I have a problem with people banging on the door morning, noon and night,” Francisca Ramos said this week.